Abstract: NSE36 steel plates were welded using solid corrosion resistant welding wires in three kinds of heat input. Corrosion test and potentiodynamic polarization test were conducted to the welded joints. The effect of heat input on corrosion resistance of weld line was studied in terms of microstructure, inclusions and corrosion morphology of the weld line with OM, SEM and EDS. The results show that the microstructure of weld lines in different inputs mainly consisted of acicular ferrite and a little proeutectoid ferrite. The content of acicular ferrite in weld lines decreased with the heat input increasing. The dominant inclusions in weld metals were composite oxides of Mn and Si, and less Ti and Al. The size distribution of inclusions in three weld lines was similar. As the heat input increased, the corrosion tendency and corrosion rate decreased.